Hi cricketer
I assume that you mean top of leg facing front, yes as long as you injecting into the layer of fat under the skin and not into the muscle..
Other places you may inject are..
Stomach area (but not near the navel around 2inches away)
Buttocks
the fatty bits know as love handles above the hips
The upper arm..
I've personal never tried the buttocks or the hip one (in 21 years)
I started off injecting into my legs, be weary though if you doing sports that use a lot of leg muscle as this can increase the effectivness of the insulin injection..
The important bit about injecting is getting the insulin into the fatty layer under the skin, and also remembering to rota your injections sites, always leave at least an inch or 2 from the previous injection... I use a insulin pump now, but when I injected I would use one side then on the next injection I used the other side, then repeat but using a diferent location within the area...